Boys will be boys” and other platitudes may condone adolescent reckless driving, substance use, or sexual promiscuity—but to write off dangerous behavior as normal would be a mistake. Because adolescent impulsivity and sensation-seeking may have physiologic as well as emotional causes,1,2excessive risk taking may be treatable.

This article discusses the neurobiology of adolescent risk taking, suggests how to determine when such behavior may be pathologic, and offers a treatment approach for at-risk teens and their parents.

CASE: ‘WHAT’S WRONG WITH OUR SON?’

Josh, age 17, is brought to the adolescent psychiatry clinic by his distraught parents, who report their son has undergone a “personality change” over the past 2 years. They recall that he was respectful, studious, and soft-spoken until age 15. Since then, he has been skipping school, staying out late at night with his friends, and “obsessed” with TV poker games.

His parents recently discovered he has been gambling for money, which greatly upsets them. They also found a pack of cigarettes in their son’s car and are concerned that he might be using other substances. What finally prompted the psychiatric visit was Josh’s recent traffic citation for driving 25 miles over the speed limit.

CAUSES OF RISK TAKING

Normal development. In the absence of psychopathology, adolescent risk taking appears to be a normal development stage that is vital to successful transition to adulthood. This assumes that adolescents such as Josh learn to moderate their behavior and avoid long-term negative consequences.

Impulsivity and sensation seeking are recognized as key factors in adolescent risk taking Box 1.1-4 Apparently, these traits result primarily from incomplete neural circuit maturation. Adolescent brain regions involved in impulsivity and risk taking are also involved in reward, and these centers exhibit an exaggerated response to stimuli.5This amplified response may help explain an adolescent’s propensity for risky behavior.

Adolescent risk-takers have been found to be more self-confident, to feel more accepted, and to be better liked than their more-cautious peers.6

Psychiatric comorbidity. Excessive risk taking can be associated with psychiatric illness, including bipolar mania, psychosis, substance abuse, and impulse control disorders. Individuals with borderline personality and other cluster B disorders have marked impulsivity and thus are prone to risky behavior.

Alcohol. 40% of adult alcoholics report having had their first alcoholism-related symptoms between ages 15 and 19.1

Gambling. 10% to 14% of adolescents engage in problem or pathologic gambling, and gambling typically begins at age 12.2

Automobile crashes are the leading cause of death among North American adolescents; both sexes ages 16 to 20 are at least twice as likely to be in a motor vehicle accident as are drivers ages 20 to 50.3

STDs. Each year, 3 million U.S. adolescents contract a sexually transmitted disease (STD). HIV infection is the seventh leading cause of death for Americans ages 13 to 24.4

Sexual activity. Adolescents are more likely than adults to engage in impulsive sexual behavior, to have multiple partners, and to fail to use contraceptives. Younger teens (ages 12 to 14) are more likely to engage in risky sexual practices than older teens (ages 16 to 19).4

CASE CONTINUED: JUST ‘HAVING FUN’

When interviewed alone, Josh admits to “occasional” truancy, which he attributes to being “bored” with school and wanting to spend time with his friends “doing fun stuff, like going to the beach.” He admits to gambling for money and smoking a half-pack of cigarettes daily, as well as drinking beer and smoking marijuana “a few times a week.”

Josh says he engages in these activities “because they’re fun,” and states he is annoyed by his parents’ concern. He blames the speeding ticket on “not paying attention.” He admits to drinking and driving but claims he always feels “in control.”

He also reports he has been sexually active since age 16 and often has had unprotected intercourse. When asked if he is concerned that he might contract a sexually transmitted disease or impregnate his partner, Josh appears ambivalent.

IMPULSIVITY IN ADOLESCENCE

Josh is engaging in numerous impulsive behaviors. Adolescents generally are more impulsive than adults, as demonstrated by their significantly higher impulsivity scores on standardized tests.7 Furthermore, as measured by improved response inhibition (go/no go tasks), the level of adolescent impulsivity is inversely related to age.8

Problem behavior syndrome. High impulsivity is predictive of problem gambling, drug use, and risky driving and sexual practices later in life.1,2,9-11 Adolescents with what some authors describe as a “problem behavior syndrome” engage in behaviors—such as substance use, risky sexual behavior,12 gambling,13 and reckless driving14—that share a common trend toward impulsivity.

Impaired data processing. Decision making has been proposed as a three-part cognitive process:

accumulating sensory input

processing this input and formulating a behavioral response appropriate to the situation

Impulsivity is believed to result from impaired ability of the brain to process accumulated information or to formulate a response to it—or both. Impulsive individuals thus experience impaired data processing, in which they:

misjudge the likely risk of a given action or overestimate their ability to accomplish a task

show impaired response inhibition and thus find it difficult to resist an impulse to participate in a given activity.

Sensation seeking. Adolescents who exhibit risk-taking behavior may wish to experience the thrill of the behavior (sensation or novelty seeking). Alcoholic or drug-dependent individuals and those who engage in pathologic gambling or take chances while driving also demonstrate significantly impaired decision making.15-17 Adolescents who engage in these and other problem behaviors have similarly scored high on sensation-seeking scales.10,18

DECISION-MAKING BIOLOGY

At least four neural circuits process decisions, weighing the risks and benefits of a given situation and formulating a response. These circuits are:

Functional imaging studies—including MRI and PET, EEG, and electrophysiology—have confirmed that these four brain regions are integral to response inhibition and show abnormal activity in impulsive individuals.20,21 Indeed, prefrontal cortex damage has been extensively documented to cause marked impulsivity, poor decision making, and an increased propensity for substance abuse and dependency.1

Functional imaging studies also have shown that adolescents appear to use these neural regions inefficiently during decision making. Extensive areas of the involved brain regions are activated in individuals ages 8 to 20, whereas only focal activation occurs in adults.22

Dopamine. The nuclear accumbens (NA) plays an important role in processing afferent excitatory glutamatergic projections and then instigating the given response.23 Dopamine is released in the NA in response to a long list of stimuli, including:

exposure to substances

natural rewards such as food or sex

stimulating situations, such as playing video games, gambling, or thrill seeking.2

Novel experiences and rewards that are delivered erratically cause an elevated dopamine release in the NA. This may explain, in part, the excitement one gains from activities with unpredictable outcomes, such as gambling, bungee jumping, parachuting, white-water rafting, or taking risks while driving.

As rewarding stimuli are re-experienced, dopamine response accelerates in magnitude, and the reward becomes progressively stronger as the experience is repeated. This repeated dopamine release in the NA changes the cellular proteins involved in signaling pathways thought to be associated with the transition from impulsive to compulsive behavior.2 Therefore, addiction may be caused by neurocircuitry changes induced by repeated dopamine release. Similarly, persons who engage in impulsive behavior may have hypersensitive dopamine-related reward circuitry, which may, in part, explain their predisposition to addictive behavior.

Activity within this network is modulated by excitatory glutamatergic transmission and inhibitory GABAergic transmission within the cortices and by dopaminergic and serotonergic transmission within the VTA and raphe nuclei, respectively.2,20 Although all of these neurotransmitters have been implicated in impulsivity, dopamine and serotonin have been studied most extensively (box 2).1,2,23-26

CASE CONTINUED: PSYCHIATRIC WORKUP

Josh clearly is engaged in worrisome behavior with potential long-term consequences. To evaluate him for underlying psychopathology, the psychiatrist used a structured psychiatric exam, Minnesota Multi-phasic Personality Inventory (MMPI), and SNAP-IV Rating Scale for ADHD (see Related resources). Josh endorsed some depressive symptoms—which were also evident on the MMPI—but did not meet DSM-IVTR criteria for major depressive disorder. Neither were his symptoms diagnostic for any other Axis I or Axis II disorder.

Given the risk of harm and likelihood of worsening behavior over time, the psychiatrist schedules Josh for weekly psychotherapy and possible medication.

Psychosocial interventions are discussed with Josh’s parents, including monitoring his activities, restricting access to peers who have been a poor influence, reinforcing good behavior, and enlisting help from teachers and his friends’ parents. The effect of these interventions is to be explored in follow-up visits.

After months or years of conflict with their child, the parents of an adolescent with severe risk-taking behavior are often distraught and frustrated. You can comfort them by explaining:

the biology of adolescent risk taking

how you will treat such behavior in their adolescent

and their role in the treatment plan.

Often the child’s behaviors have weakened their marriage, given adolescents’ tendency to divide and manipulate their parents. To help them set and maintain limits in the face of their child’s hostility:

Educate them to communicate with each other, to maintain a united front, and to set firm limits for their adolescent. For example, recommend that they:

forbid cell phone use while the adolescent is driving

limit the number of passengers allowed in the adolescent’s car to reduce distractions

reduce the amount of money and free time available to the adolescent.

Counsel them that they are unlikely to receive the child’s respect or affection in the short term. Reassure them, however, that the child will thank them for their firm guidance after he or she matures to adulthood.

DEFINING DEGREES OF RISK

Although no criteria differentiate “normal” from “pathologic” risk taking, the definition of taking a risk implies potential adverse consequences. In evaluating the impulsive adolescent, it is important to determine which behaviors:

Acceptable. Risk taking is acceptable if the potential adverse outcome is relatively benign and the adolescent is likely to learn from the experience. For example, driving 10 miles over the speed limit and receiving a ticket can lead to stricter observance of the speed limit.

Pathologic. Josh clearly exhibits risky behaviors that one would reasonably consider “pathologic,” as they carry potentially severe consequences that exceed any possible developmental gain. For example, drinking and driving can result in a DUI citation and/or a motor vehicle accident with physical injuries or death.

An early refill request for psychostimulants for your college-age patient

﻿Mr. R, age 18, who has been taking amphetamine/dextroamphetamine, 10 mg/d, twice a day, for attention-deficit/hyperactivity disorder since he was age 10, comes to see you shortly after beginning college asking to refill earlier than usual. He says his symptoms are worse since beginning college and he is finding it difficult to focus in class and keep up with the heavy course work. He says he has been taking an extra 10 mg when he “needs the extra boost.” He asks for an early refill and increased dosage. How do you proceed?

Switch to an extended release formulation and increase the dosage to 30 mg/d

Switch to lisdexamfetamine, 30 mg/d

Prescribe amphetamine/dextroamphetamine, 10 mg, on an as-needed basis

Tell Mr. R to take his current prescription as prescribed and discuss the dangers of stimulant abuse. Reassess his symptoms at the next visit.